Conventionally, a form of a document commonly used in the world has generally been a paper document, but progress of the Internet or intranet has given a birth to a hypertext as an electronic document which can compete for the first time against the paper document. This hypertext document is a document written in HTML in a narrow sense, and includes all the electronic documents which can link between documents such as PDF documents by Adbe and a portion of an SGML document by CALS (namely, between a button comprising a particular word, a text, a symbol or graphics and a document) in a broad sense.
Specifically, the hypertext is a collection of linked texts (electronified documents) and is the basic concepts for multimedia software with which texts hierarchically related to each other can simultaneously be referred from multiple sites to in an arbitrary order through a link structure. Therefore, each document of this hypertext includes information for forming the link structure (namely, information as a hypertext) in addition to information visually provided to users.
By the way, in the field of computer technology, a search engine is provided as a means of searching for a document linked to a particular word (keyword) from vast number of undefined documents. It should be noted that in the conventional type of search engine a keyword is not entered in a document but it is entered in a particular dialog box.
However, although there are many advantages in the hypertext, a jump can be made only to a linked page (document), and so, when a user wants to have information related to any word not linked to some other documents, it is necessary to actuate a search engine or the like and perform a search (a keyword search or a global search), which makes the operation complicated, and also linkage among documents is not easy therefore it is not always easy to use the hypertext.
In the conventional type of hypertext, an operation with one button can be linked only to one document (page), which does not allow a plurality of documents to be referred to with one button. Especially, the Intranet documents are highly specialized so that there may exist a plurality of information that the user wants to refer to with one button, hence convenience of use and workability are not sufficient for the situation.
In the conventional type of search engine, a user interface is of inferior performance as compared to a hypertext and the operating method is also different, and so, insufficient workability and convenience are found in actuation of a search engine and performance of a search during operation of the hypertext. Especially, in a browser function for displaying and operating a hypertext on a screen, it is general to operate only with a pointing device such as a mouse, so that entry of a keyword into a dialog box of the search engine through a keyboard disturbs the flow of work.